Led-Based Light Bulb

ABSTRACT

A light source ( 10 ) comprises a light engine ( 16 ), a base ( 24 ), a power conversion circuit ( 30 ) and an enclosure ( 22 ). The light engine ( 16 ) comprises at least one LED ( 12 ) disposed on a platform ( 14 ). The platform ( 14 ) is adapted to directly mate with the base ( 24 ) which a standard incandescent bulb light base. Phosphor ( 44 ) receives the light generated by the at least one LED ( 12 ) and converts it to visible light. The enclosure ( 22 ) has a shape of a standard incandescent lamp.

BACKGROUND

The present application relates to the art of LED lighting systems. Itfinds particular application in the light packages traditionallyemployed in an incandescent light source and will be described withparticular reference thereto. Those skilled in the art will appreciatethe applicability of the present invention to the applications where ause of an LED light source in a traditional bulb light package canprovide advantages such as increased durability, light output stabilityand energy savings.

Typically, incandescent light bulb packages utilize a light source thatincludes an incandescent filament within a glass enclosure. However, theincandescent filaments are fragile and tend to gradually degrade duringlifetime of a bulb causing the useful light output generated by thefilaments to decrease over time. The increasing fragility of thefilament with age eventually leads to breakage. Typical incandescentlight bulbs have a mean life of 500 to 4,000 hours.

Light emitting diodes (LEDs) present an attractive alternative as alight source in a light bulb package. A low-power, solid-state LED lightcould last up to 100,000 hours (eleven years), far outdistancing thelife of a typical incandescent bulb. When the LED degrades to half ofits original intensity after 100,000 hours, it continues operating witha diminished output. In the state of operation with the diminishedoutput, the LEDs are still ten times more energy-efficient thanincandescent bulbs, and about twice as efficient as fluorescent lamps.Besides producing little heat and being energy-efficient, LEDs aresolid-state devices with no moving parts. LEDs characteristics do notchange significantly with age, and they are not easily damaged by shockor vibration. This makes LED lighting systems very reliable. The smallshape and low heat generated by the LEDs enables lighting systems totake on various shapes and sizes.

A widespread use of the LED lighting systems have been limited becausethe consumers are accustomed to seeing and purchasing the traditionalbulb lights. The number of various bulb light packages on the market istremendous. In addition to the unique cosmetic appearance, the packagesdiffer in luminescent levels, color temperatures, electricalrequirements, and other characteristics. One approach has been todirectly retrofit the LED into the existing light package. However, thesingle LED does not produce the light output of the same opticalcharacteristics as each existing incandescent bulb lamp. In addition,the LEDs emit highly directional light resulting in a narrow light angleand require different input power.

The present invention provides a new LED lamp.

BRIEF DESCRIPTION

According to one aspect of the application, a light source is disclosedA light engine generates light of one of a plurality of wavelengths. Thelight engine includes a platform and at least one LED disposed on theplatform. An enclosure surrounds a light generating area of the lightengine. A base includes a heat sink for conducting thermal energy awayfrom the at least one LED. The light engine is mounted onto a heat sink.A conversion circuit supplies electric power to the light engine.

One advantage of the present application resides in providing a commonlight engine that is used across various bulb platforms.

Another advantage resides in providing an adaptable and scalable LEDlamp design.

Still further advantages and benefits of the present invention willbecome apparent to those of ordinary skill in the art upon reading andunderstanding the following detailed description of the preferredembodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may take form in various components and arrangements ofcomponents, and in various steps and arrangements of steps. The drawingsare only for purposes of illustrating the preferred embodiments and arenot to be construed as limiting the invention.

FIG. 1 schematically shows a cross-section of an LED-based lamp;

FIG. 2 schematically shows a top view of a platform including LEDs;

FIG. 3 schematically shows a cross-section of an LED-based lamp whichincludes a heat dissipating slug;

FIG. 4 schematically shows a cross-section of an LED-based lamp whichincludes an extended heat dissipating slug;

FIG. 5 schematically shows a cross-section of an LED-based lamp whichincludes a phosphor panel; and

FIG. 6 schematically shows a cross-section of an LED-based lamp whichincludes a filament light guide.

DETAILED DESCRIPTION

With reference to FIGS. 1 and 2, a lighting system 10 includes one ormore LEDs 12 which are positioned on a mounting platform 14, defining alight engine 16. Wire leads 18, 20 are provided for powering the LEDs12. The LEDs 12 is one of inorganic and organic light emitting deviceswhich emit light in a spectrum from UV to infrared. Variations inoptical performance, viewing angles, and intensity levels are achievedby arranging the LEDs in different patterns. The lighting system 10includes a light cover or enclosure 22. Preferably, the enclosure 22 isa traditional bulb-shaped enclosure. Optionally, the enclosure 22 is acustom built enclosure to provide non-uniform light output to createspecial visual effects. It is contemplated that the enclosure 22 can bespherical, elliptical, cylindrical, domed, squared, n-sided, or anyother shape. Preferably, the enclosure 22 is built of light transparentor translucent materials, or a combination thereof. The enclosure 22materials are selected from glass, plastic, acrylic, polycarbonate, orother suitable materials.

Preferably, the platform 14 is a substrate on which a semiconductor maybe grown. The platform 14 can be one of sapphire, gallium arsenide,silicon carbide, gallium phosphorous, gallium arsenide, gallium nitride,or other suitable material. It is also contemplated that the platform 14can be a printed circuit board, heatsink, or any other suitable meansfor mounting the LEDs 12. The LEDs 12 are attached to the platform 14 byone of solder, wirebonding, thermosonic, thermocompression, electricalconductive adhesives, thermal conductive adhesives, other suitablemeans, or a combination of the above. It is also contemplated that theLEDs 12 can be adjacent to or manufactured as an integral part of thecover 22.

The platform 14 is adapted to be directly mounted into a base or socket24. In one embodiment, the base 24 has a receptacle into which the lightengine 16 is plugged in. Preferably, the base 24 is one of thecommercially available light bulb sockets for easy field exchange andretrofitting of the light bulb with the LED light engine 16 such thatthe enclosure 22 can be fitted over the light engine 16. E.g., in oneembodiment, the base 24 is one of commercially available incandescentlight sockets such as 6S6 screw base, 194 wedge base, or other. Suchdesign allows the conventional lamp to be replaced with a variety ofdifferent LED light engines without modification to the lamp socket orto the lamp enclosure. Optionally, the base 24 is custom manufactured.At least one heatsink 26 is integrally disposed in thermal communicationwith the light engine 16 and the base 24 to take the heat away from theLEDs 12. The heatsink 26 is constructed from the material capable ofconducting the heat away from the LEDs 12. Examples of suitablematerials include copper, aluminum, silicon carbide, boron nitride andothers known to have a high coefficient of thermal conductivity.

Preferably, an index matching material 28 is applied to encompass thelight engine 16 to improve the light extraction. The index matchingmaterial is selected from silicones, acrylics, epoxies, thermoplastics,glasses and any other appropriate materials. Optionally, an indexmatching fluid, which preferably serves as a thermal spreading medium,is present between the light engine 16 and the cover 22. The fluid isselected from solids, gels, liquids, fluorocarbon coolants, luminescentmaterials and others to create a desired visual effect. Additionally,reflective or translucent particles may added to the fluid for furthervisual effects. The cover 22 works together with the internal fluid tooptimize light extraction and/or provide visual effects. In oneembodiment, the index matching material 28 is structured to providelensing.

In order to provide suitable electrical power to the LEDs 12, thelighting system 10 includes one or more of an electric power conversioncircuit, or control electronics, or power electronics circuits 30, whichare preferably integrated with the light engine 16. Alternatively, theelectric power conversion circuit 30 can be adjacent the light engine16, located within the base 24, or disposed remotely from the lightingsystem 10. In one embodiment, the electric power conversion circuitincludes an AC/DC converter which permits the LED-based lighting system10 to be powered by a standard domestic 120VAC or international 220VACuser voltage. Such circuitry makes the LED lamp a true replacement for abulb light. Preferably, the power electronics circuits 30 are two- orthree-dimensional structures to provide minimal dimensions. In oneembodiment, the electric power conversion circuits 30 are flexiblecircuits. Optionally, the electric power conversion circuits 30 arenon-planar circuit boards.

With reference to FIG. 3, the lighting system 10 includes a heatdissipating slug 32. The heat dissipating slug 32 is disposed in athermal communication with the base 24 to conduct the heat from thelight engine 16 into the base 24. Optionally, the heat dissipating slug32 transfers the heat from the light engine 16 into the air. Preferably,the heat dissipating slug 32 includes a plurality of radial fins 34disposed about an outer periphery of the slug 32.

With reference to FIG. 4, the heat dissipating slug 32 extends beyondthe base 24 to transfer the heat from the light engine 16 into the air.

Optionally, the base 24 includes at least one of thermoelectric cooling,piezo synthetic jets, qu-pipes, heat-pipes, piezo fans and electricfans, or other forms of active cooling.

With reference to FIGS. 5 and 6, the lighting system 10 includes awavelength converting material such as organic or inorganic phosphor.The phosphor can be located in any suitable location, such as integratedinto the LED 12, at a light guide 36, coated inside or outside the cover22, contained within the cover 22, or a combination thereof.

In one embodiment, the enclosure 22 includes transparent organicphosphors which are preferably coated on an inside, or outside surfaceof the enclosure 22, or a combination thereof It is also contemplatedthat the phosphors can be dissolved, melted, coextruded, or dispersed byany other means within the walls forming the enclosure 22. Preferably,the phosphor distribution is uniform. In one embodiment, the phosphordistribution is non uniform to create preselected patterns, figures,special visual effects of different colors, and other effects. It isalso contemplated that both transparent and conventional non-transparentphosphors can be used to create special effects, patterns, or figures.In one embodiment, the enclosure 22 is frosted or otherwise treated toprovide special visual effects. Examples of the organic transparentphosphors are the BASF Lumogen F dyes such as Lumogen F Yellow 083,Lumogen F Orange 240, Lumogen F Red 300, and Lumogen F Violet 570. Ofcourse, it is also contemplated that other phosphors such as the rareearth complexes with organic component described in the U.S. Pat. No.6,366,033; quantum dot phosphors described in the U.S. Pat. No.6,207,229; nanophosphors described in the U.S. Pat. No. 6,048,616, orother suitable phosphors can be used.

With continuing reference to FIG. 5, the UV light rays 40 are emitted bythe LEDs 12 and converted into white or visible light 42 by a phosphor44. The phosphor 44 preferably includes two or more phosphors to convertthe emitted light 40 to the visible light 42, although single componentphosphors are embodied for saturated color light generation as well. Thevisible light 42 exits through the enclosure 22. In this embodiment, thephosphor mix 44 is disposed about or within a light guide 36 which is aplanar panel disposed above the LED 12 such that the majority of thelight rays 40 strike the panel.

With reference again to FIG. 6, the light guide 36 is a filament whichis disposed within the enclosure 22 to create a “filament-look” LEDbased lighting system. More specifically, phosphor 44 is applieddirectly to the LED 12 such that the emitted light 40 is converted intovisible light 42 at the LED 12. The visible light 42 strikes the lightguide 36 and adapts the filament shape to simulate a “filament-look”light bulb. Alternatively, a suspended reflector may be used to simulatethe filament shape. The reflector can be “wadded” tin foil, a coiledaluminized spring, or the like. Optionally, the light guide 36 is acoiled fiber optic with surface, internal, or other diffusers, such asfrustrated TIR (Total Internal Reflection) diff-users, to allow thelight to escape at the desired locations.

The invention has been described with reference to the preferredembodiments. Modifications and alterations will occur to others upon areading and understanding of the preceding detailed description. It isintended that the invention be construed as including all suchmodifications and alterations insofar as they come within the scope ofthe appended claims or the equivalents thereof.

1. A light source (10) comprising: a light engine (16) for generatinglight of one of a plurality of wavelengths, the light engine (16)including: a platform (14), and at least one LED (12) disposed on theplatform (14); an enclosure (22) surrounding a light generating area ofthe light engine (16); a base (24) including a heat sink (26) forconducting thermal energy away from the at least one LED (12), intowhich heat sink (26) the light engine (16) is mounted; and a conversioncircuit (30) for supplying electric power to the light engine (16). 2.The light source as set forth in claim 1, further including: aluminescent converting element (44) to receive the light generated bythe light engine (16) and convert at least some of the received light tovisible light.
 3. The light source as set forth in claim 2, furtherincluding: a light guide (36) disposed within the enclosure (22).
 4. Thelight source as set forth in claim 3, wherein the luminescent convertingelement (44) is adjacent at the least one LED (12).
 5. The light sourceas set forth in claim 4, wherein the light guide (36) provides anappearance of a filament.
 6. The light source as set forth in claim 4,wherein the light guide (36) comprises an optical fiber with one ofinternal diffusers, external diffusers, and other frustrated TIR (TotalInternal Reflection) features to allow the light to escape atpreselected locations.
 7. The light source as set forth in claim 3,wherein the light guide (36) comprises a reflector.
 8. The light sourceas set forth in claim 7, wherein the reflector is comprised of areflective metal.
 9. The light source as set forth in claim 3, whereinthe luminescent converting element (44) is disposed on or within thelight guide (36).
 10. The light source as set forth in claim 2, whereinthe luminescent converting element (44) is disposed on or in theenclosure (22).
 11. The light source as set forth in claim 10, whereinthe luminescent converting element (44) includes a transparent phosphor.12. The light source as set forth in claim 1, wherein the transparentphosphor comprises one of: an organic phosphor, an organic complex of arare earth metal, a nanophosphor, and a quantum dot phosphor.
 13. Thelight source as set forth in claim 10, further comprising: one of anindex matching material and a lensing material encompassing the at leastone LED (12).
 14. The light source as set forth in claim 1, wherein thebase (24) is adapted for mating with the light engine (16).
 15. Thelight source as set forth in claim 1, wherein the heat sink (26)comprises: a slug (32) inserted into the base (24) for conducting thethermal energy from the at least one LED (12) to at least one of thebase (24) and ambient air.
 16. The light source as set forth in claim15, wherein the slug (32) comprises: a plurality of fins (34) disposedin one of a radial and a cylindrical tube longitudinal design about anouter periphery.
 17. The light source as set forth in claim 1, whereinthe heat sink (26) extends radially from the base (24) to conduct thethermal energy to ambient air.
 18. The light source as set forth inclaim 1, wherein the conversion circuit (30) comprises: an AC to DCconverter.
 19. The light source as set forth in claim 1, wherein theplatform (14) comprises one of: a metal clad, FR4, and CEM-1 printedcircuit board hosting the at least one LED.
 20. The light source as setforth in claim 1, wherein the enclosure (22) comprises a substantiallytransparent enclosure of a variety of shapes
 21. The light source as setforth in claim 20, wherein the enclosure (22) comprises a lightdiffusing coating.
 22. The light source as set forth in claim 1, furthercomprising: an index matching fluid between the light engine (16) andthe enclosure (22).
 23. A modular adaptable LED lighting system (10)comprising: a screw base module (24); at least two light modules (16)having different light emission characteristics, each light module (16)including: a platform (14) which is adapted for mating with the basemodule (24), and at least one LED (12) disposed on the platform (14) forgenerating light in a range from ultraviolet to infrared wavelenthgs; anenclosure (22), which surrounds the light produced by the light module(16) such that at least a portion of the light is transmitted throughthe enclosure (22); and a power module (30) for energizing the at leastone LED (12).